<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <!-- 新 Bootstrap5 核心 CSS 文件 -->
    <link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/5.3.0/css/bootstrap.min.css">

    <!--  popper.min.js 用于弹窗、提示、下拉菜单 -->
    <script src="https://cdn.staticfile.org/popper.js/2.9.3/umd/popper.min.js"></script>

    <!-- 最新的 Bootstrap5 核心 JavaScript 文件 -->
    <script src="https://cdn.staticfile.org/twitter-bootstrap/5.3.0/js/bootstrap.min.js"></script>
</head>
<body>

<div class="dropdown">
  <button type="button" class="btn btn-primary dropdown-toggle" data-bs-toggle="dropdown">
    下拉菜单按钮
  </button>
  <div class="dropdown-menu">
    <a class="dropdown-item" href="#">链接 1</a>
    <a class="dropdown-item" href="#">链接 2</a>
    <a class="dropdown-item" href="#">链接 3</a>
  </div>
</div>

</body>
</html>